[4.x] Guard against NPE during early invocation of Span.current() #8257
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Signed-off-by: Tim Quinn <tim.quinn@oracle.com>
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| logging that adds the current span to each message), then this method can be invoked before the static initializer has | ||
| completed and, therefore, before TRACER_PROVIDER is assigned. | ||
| */ | ||
| return (TRACER_PROVIDER == null) ? Optional.empty() : TRACER_PROVIDER.currentSpan(); |
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I think that this is creating a bug. We should never reach this method within initalization.
If we do, then we should change the way we initialize, rather than checking if a constant field is null
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As I mentioned in our DMs, we could add a static boolean that indicates if the static initializer is in progress or not. Then currentSpan could check that boolean and, if true, return Optional.empty() right away rather than trying to use TRACER_PROVIDER. That might look slightly less odd than checking a supposedly final field for null, but it amounts to the same thing: checking whether the static initializer is in-progress or not.
As we also discussed, I will also add code to throw exceptions from other methods that rely on TRACER_PROVIDER but are void or have non-Optional return types.
Description
Resolves #8254
See description for details and related 3.x PR #8256 for explanation.